Manage diabetes medications during fasting

How should diabetes medications be managed while fasting? Fasting for morning labs usually doesn't require adjustments. But other fasts vary. For example, patients may fast from dawn to dusk during Ramadan or from sundown to sundown during Yom Kippur or 18 hours/day with some intermittent fasting diets. Help individualize a plan based on medications, and fast duration...

Medications that rarely cause hypoglycemia include metformin, pioglitazone, gliptins (Januvia, etc.), and GLP-1 agonists (Victoza, etc.). These can generally be continued during intermittent or religious fasts but may need to be held before procedures. Labelling advises holding most SGLT2 inhibitors (Jardiance, etc.) before surgery due to the risk of ketoacidosis. Some experts may also recommend holding them before procedures or religious fasts if dehydration may occur. Consider this a downside of using SGLT2 inhibitors in patients planning religious fasting or intermittent fasting diets.

Insulin and sulfonylureas are more significant culprits for hypoglycemia. In general, advise holding mealtime insulin or sulfonylureas once the patient stops eating. Consider holding sulfonylureas 24 to 36 hours before a longer fast (e.g., 24 hours).

• For basal insulin, administer about half the usual dose if the patient is well controlled or at higher risk for hypoglycemia (e.g., elderly, kidney impairment). Otherwise, consider reducing the dose by about one-third.
• Suggest reducing doses of NPH or a long-acting analog (Lantus, Levemir, etc.) at the start of the fast. For Tresiba, reduce the dose the day before the fast, as it lasts almost two days.

Recommend frequent blood glucose monitoring while fasting in patients on insulin or sulfonylureas. Advise other patients to check if they experience symptoms of hypoglycemia (e.g., feeling shaky, dizzy, sweaty). Suggest breaking the fast for glucose below 70 mg/dL (3.9 mmol/L) or if patients have symptoms with glucose below 80 mg/dL (4.4 mmol/L).

REFERENCES

• Grajower MM. 24-Hour Fasting with Diabetes: guide to physicians advising patients on medication adjustments prior to religious observances (or outpatient surgical procedures). Diabetes Metab Res Rev. 2011 Jul;27(5):413-8. Available at: https://pubmed.ncbi.nlm.nih.gov/21309050

  Ibrahim M, Davies MJ, Ahmad E, Annabi FA, Eckel RH, Ba-Essa EM, El Sayed NA, Hess Fischl A, Houeiss P, Iraqi H, Khochtali I, Khunti K, Masood SN, Mimouni-Zerguini S, Shera S, Tuomilehto J, Umpierrez GE. Recommendations for management of diabetes during Ramadan: update 2020, applying the principles of the ADA/EASD consensus. BMJ Open Diabetes Res Care. 2020 May;8(1):e001248. Available at: https://pubmed.ncbi.nlm.nih.gov/32366501 

  Diabetes Canada, Ramadan and Diabetes: http://guidelines.diabetes.ca/health-care-provider-tools/ramadan-and-diabetes